We stayed at Lancaster gate from 12/24 to 1/1. The hotel staff was always very friendly and helpful when needed. Someone was always at the front desk, the bar, and the restaurant. Hotel is close to multiple tube stations, Hyde Park, and Paddington Station for the trains. The beds were comfortable, the pillows were plush, not too firm not too soft, and the bed was warm. The bathroom even had a towel warmer :) One of the largest downsides was the noise. The door to our room left about 1.5 inches of space between the bottom of the door and the floor. Therefore, ANYTHING happening in the hallway we heard clearly at all hours of the night. We solved the issue by stuffing towels under the door but the door should definitely touch the floor...
Additionally, the walls seemed to be paper thin. Often times, at 6am, we heard our neighbors up and talking and moving around. There wasn't a fan in the room to provide any sort of white noise. Once again, easily fixed by downloading a white noise app on my phone and playing that all night.
All in all, nothing huge that would turn me off from this hotel. I would definitely stay here again, and have the white noise app on my phone :)